Justified True Belief

(●) The friar who took Aristotle, the pagan philosopher his own university had banned, and put him to work for the gospel. + When Thomas of Aquino was a boy, the books of Aristotle on nature and the soul were forbidden reading at the University of Paris. By the time he died they were the backbone of the arts course, and the reason was largely him. He had spent his working life doing something that sounds obvious now and was risky then: reading the best pagan science available, keeping what was true, arguing against what was false, and refusing to believe that God could be embarrassed by an honest fact. For a Christian reader that habit is the whole point of him. Aquinas is where the claim that faith and reason are two roads out of the same city gets its most careful defense: he held that the existence of God can be argued for from the world anyone can see, that Scripture tells us things no argument could have reached, and that the two can never contradict each other, because the same God is the author of both. And the settlement he worked out is still doing work seven centuries later. When a philosopher today argues for God from causation, or from contingency, which is the plain fact that the things around us exist and might just as easily never have existed at all, the ground being fought over is mostly ground he mapped, and the argument is either developing something he wrote or answering it. He worked at a pace that is hard to picture. In little more than twenty years he produced biblical commentaries, commentaries on twelve works of Aristotle, hundreds of articles of formal disputation, and two enormous summaries of Christian teaching, dictating to several secretaries in turn. His last and greatest book, the Summa Theologiae, runs to five hundred and twelve questions and nearly two thousand seven hundred short articles, and he left it unfinished.

(●) c. 1225 AD: Born in a hill castle south of Rome, the youngest son of a family with plans for him. + Thomas was born around 1225 at Roccasecca, a fortified village belonging to his father Landulf, one of the lesser counts of Aquino, in the Kingdom of Sicily. His mother Theodora came from a family of the Neapolitan nobility. The exact year is not certain: the earliest biographers disagree, and at his death there was already a dispute about how old he was, so "about 1225" is the convention rather than a record. Nine miles from the castle stood Monte Cassino, the abbey Benedict of Nursia had founded seven centuries earlier and the most prestigious monastery in Latin Christendom. At about the age of five Thomas was handed over to it as an oblate, which is a child given by his family to be raised by monks. To modern ears that sounds like abandonment, and it was nothing of the kind; it was a career move, and a shrewd one. An abbot of Monte Cassino held land, tenants and political weight, so a well-connected boy placed there young might reasonably be expected to end up wearing the abbot’s ring. What his teachers there remembered afterwards was a quiet child who kept asking one question. William of Tocco, who gathered up the recollections of people who had known him, reports that the boy would ask the monks, over and over, "What is God?" The story comes from a life written to support his canonization, so it is a memory polished by devotion, and it should be held loosely. It is still a fair enough summary of what he did with the next fifty years.

(●) 1239 AD: A war between emperor and pope sent him to Naples, where he met Aristotle and the friars. + The emperor Frederick II and Pope Gregory IX were at war, and Monte Cassino sat directly between them. In 1239 imperial troops occupied the abbey and the young students were sent home. Thomas, then about fourteen, went instead to the university Frederick had founded in Naples in 1224. Naples was the right accident. Because it was the emperor’s school rather than the church’s, it taught what Paris would not. Aristotle’s books on nature and the soul had come back into the Latin West only a generation earlier, carried in by way of Arabic and Greek manuscripts, and Paris had forbidden them as lecture material in 1210 and then again in 1215. At Naples a master named Peter of Ireland taught them freely, and taught the newly translated commentators along with them, Averroes above all. Averroes and Avicenna were Muslims, Maimonides was a Jewish rabbi, and the tradition of Arabic philosophy all three belonged to had been working over these books since the ninth century while the West did not have them. So Thomas met the most powerful account of the physical world anyone had produced, and, as it happened, he met it without anyone standing over him telling him to be afraid of it. He also met the Dominicans. The Order of Preachers was not yet thirty years old, and it was an order of friars rather than monks, which is a real difference and not a matter of vocabulary. A monk takes a vow of stability, meaning he stays in his monastery; a friar begs his bread, travels, preaches, and in this particular order studies hard, because Dominic had founded it to answer heresy with argument rather than with force. The friars had a house in Naples, and sometime around 1244 Thomas, still a teenager, asked to join them.

(●) 1244 AD: His brothers seized him on the road and his family held him prisoner for about a year. + A Benedictine abbot in the family was something the Aquinos could accept, and had in fact been counting on. A begging friar was another matter entirely, because it meant their youngest son would own nothing, inherit nothing, and walk the roads on foot in a white habit for the rest of his life. His superiors, expecting exactly this kind of trouble, sent him north toward Rome and then Paris. His brothers, officers in Frederick’s army, caught up with him near Acquapendente and brought him home under guard. He was held in the family castles at Monte San Giovanni and Roccasecca for the better part of a year, while his mother and sisters worked on him by turns. The most famous story of the captivity comes from the testimony gathered for his canonization: that his brothers sent a woman into his room to break his resolve, and that Thomas drove her out with a burning brand snatched from the fire. It is a story told by admirers half a century later, and it should be read as such, but the detention itself is not in doubt. What the family had not counted on was that a year shut up alone with books suited him exactly. He was allowed Scripture, Aristotle, and Peter Lombard’s Sentences, the standard theology textbook of the age, and he seems to have worked through the three of them systematically, which is not how most young men spend a year under house arrest. By the summer of 1245 the resistance had collapsed, his mother had relented, and he went to the friars for good.

(●) 1245 AD: Eleven years as a student and junior teacher ended with the chair of theology at Paris. + Thomas spent those years attached to Albert of Lauingen, whom his own century already called Albert the Great, and the name was not flattery. Albert had an appetite for every branch of knowledge there was: he dissected plants and animals, wrote on minerals and on the stars, and was working his way through the whole of Aristotle, book by book, at a time when many churchmen wished the books would go away. Thomas followed him from Paris to Cologne in 1248, was ordained a priest there around 1250, and taught in Albert’s school as a junior lecturer. Fellow students found him heavy, silent, and slow, and gave him a nickname. Albert’s reply is the most quoted line in his early biographies: "We call this young man a dumb ox, but his bellowing in doctrine will one day resound throughout the world." The saying is reported by the biographers rather than by Albert himself, but the judgment behind it was certainly Albert’s, since he pushed Thomas forward at every stage. In 1252, on Albert’s recommendation, the master of the order sent him back to Paris to lecture on Lombard’s Sentences, and in 1256, at about thirty-one, he was made a master of theology, which is roughly what a full professorship is now. He got the chair over the objections of the university, and it is worth knowing why, because the quarrel followed him for the rest of his life. The secular masters, meaning the teachers who belonged to no religious order and lived on their fees, resented the friars on three counts: for holding chairs at all, for going on teaching through strikes the rest of the faculty observed, and for drawing away the best students. Their spokesman, William of Saint-Amour, wrote a book arguing that the mendicant orders, the orders that lived by begging, had no right to teach at all. Thomas answered it in print, Pope Alexander IV condemned William’s book in October 1256, and the friars kept their chairs.

(●) 1259 AD: Nine years back in Italy, where he finished the Summa contra Gentiles and began the Summa Theologiae. + The order recalled him to Italy, and he taught in Naples, then at the papal court in Orvieto, then in Rome, then at Viterbo. These are the years when the work came fastest. He finished the Summa contra Gentiles, a four-book case for the Christian faith built so that the first three books argue from reason alone and only the fourth appeals to revelation, which is to say that a reader who granted him nothing from the Bible would still have three books to get through. He also assembled the Catena Aurea, the "golden chain," a running commentary on the four Gospels stitched together entirely out of quotations from the church fathers, Greek as well as Latin. That last phrase is the difficult part: it meant hunting down texts most Western scholars of his day had never read. At Orvieto he came to know Pope Urban IV, and when Urban established the feast of Corpus Christi in 1264 the office for it, meaning the hymns and readings the church would sing on the day, was assigned to Thomas. The attribution goes back to his earliest biographers and is generally accepted, and it is a pleasant thing to know: the man best known for thousands of pages of tight argument also wrote Pange Lingua, which is still sung. In 1265 the order sent him to Rome to run a school for young Dominicans at Santa Sabina, and there he began the Summa Theologiae. His reason for starting it is stated in its opening lines and is worth noticing, because it is not the reason anyone would guess. He thought the existing textbooks were badly ordered, cluttered with useless questions, and exhausting for beginners, so he set out to write something clearer for the students in front of him. It grew into the largest and most demanding thing he ever wrote, and in time into the standard textbook of Latin theology.

(●) 1268 AD: Recalled to Paris, he fought the friars’ critics, the radical followers of Aristotle, and the theologians who wanted Aristotle shut away. + A second term as master at Paris was unusual, and the order gave him one because Paris was on fire. For a start, the old quarrel with the secular masters over the friars’ chairs had flared up again. That was the least of it. On one side stood a group of arts masters, Siger of Brabant among them. The arts faculty taught philosophy to every student before he was allowed anywhere near theology, and these men read Aristotle through the commentaries of Averroes and followed the argument wherever it seemed to lead. It led them to two conclusions in particular: that the universe had no beginning, and that there is only one intellect shared by the whole human race, so that the thinking part of you is not private property and what survives your death is not you. Thomas took the two claims quite differently. The first, he thought, could not be disproved by reason at all, though he believed it false on the authority of Genesis. The second he thought was bad philosophy and fatal to Christian hope besides, since a single shared intellect leaves nobody in particular to be raised on the last day. He wrote On the Unity of the Intellect against the Averroists in 1270, took the argument apart on Aristotle’s own ground, and ended with a challenge to answer him in the open rather than in corners. On the other side stood conservative theologians who thought the whole Aristotelian project a menace and simply wanted the books shut. In December 1270 the bishop of Paris, Étienne Tempier, condemned thirteen propositions. The list was aimed at the radicals rather than at Thomas, but the atmosphere it created did him no favours. So he was arguing on two flanks, defending the friars on a third, and administering a school, and through all of it he was producing the second part of the Summa, dictating to secretaries in relays.

(●) 1273 AD: After Mass on 6 December he stopped writing, and within three months he was dead. + In 1272 the order sent him home to Naples to found a school there, and he kept working on the third part of the Summa, the part about Christ. On 6 December 1273, while saying Mass in the chapel of Saint Nicholas, something happened to him. He never explained it. He simply stopped dictating. His secretary and closest friend, Reginald of Piperno, pressed him to go on with the book. The answer Reginald reported, and which was repeated under oath in the canonization inquiry, was this: "Reginald, I cannot, because all that I have written seems like straw to me." Readers have argued ever since about whether this was a mystical experience, a stroke, or plain exhaustion, and there is no way to settle it. We simply do not know. What is certain is that one of the most productive writers in the history of Christian theology laid down his pen at forty-eight and never picked it up again. Early in 1274 Pope Gregory X summoned him to the Second Council of Lyon. He set out on the road north, ill already, and a story preserved by his biographers says he struck his head on a fallen branch along the way. He got as far as the Cistercian abbey of Fossanova, and died there on 7 March 1274, at about forty-nine. William of Tocco reports that the Cistercians asked him for some memento of his learning, and that he spent a good part of his last strength expounding the Song of Songs to them; nothing of it survives. The Summa was left unfinished at the sacraments, and his brethren completed it by assembling a Supplement out of what he had written twenty years earlier as a young lecturer.

What He Taught

(T1) God’s existence is not obvious, but it can be argued to from the world anyone can see. + Aquinas begins where a skeptic would want him to begin, by conceding something. He does not think the existence of God is self-evident to us. Anselm of Canterbury, two centuries earlier, had argued that once you understand what the word "God" means you can see that such a being must exist. Thomas rejects that move, and his reason is disarming: we do not know what God is. The word points at something we cannot get our minds around, so nothing about God is going to be obvious to us the way "the whole is greater than the part" is obvious. What is left is the long way round, working from effects back to their cause. He sets out five of these arguments in about a page and a half, and they have been known ever since as the five ways. Each of them starts from something an ordinary person can see without a telescope or a laboratory: that things change, that things cause other things, that things come into existence and go out of it again, that some things are better than others, and that unthinking things behave as though they were aimed at a goal. The first way is the one people most often misread. It is not an argument that the chain of causes had to have a beginning long ago, with God at the far end of history lighting a fuse and stepping back. It is about right now. Aquinas uses the image of a hand and a staff: the staff moves only because the hand is putting it in motion, and if you take the hand away the whole business stops in the same instant, not eventually. His point is that a change happening now is being caused now, by something which is itself being changed at that very moment, and that a series of things all borrowing their motion from the next one along has to be anchored somewhere in something that is not borrowing at all. Take away the anchor and there is nothing left to explain why anything is moving. He is careful about what this gets you, and it is worth being as careful as he was. It does not get you the Trinity, or the Incarnation, or that God is love. The five ways end with lines like "and this everyone understands to be God," which is a modest claim about a first cause rather than a creed. The third way is the one with the longest afterlife: it argues from the things that need not have existed at all, this house, that oak tree, you, to something that must exist and could not have failed to, and it is the ancestor of the contingency arguments philosophers are still defending today.

(Q) "It is certain, and evident to our senses, that in the world some things are in motion. Now whatever is in motion is put in motion by another ... Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God." + Source: Thomas Aquinas, Summa Theologiae I, question 2, article 3 (Fathers of the English Dominican Province translation, 1920). The opening and closing of the first of the five ways (T1). Against the objections in the same article Aquinas sets Exodus 3:14, where God gives his name to Moses as I AM, and that text stands behind everything he says elsewhere about God as the one whose very nature is to exist.

(T2) Everything we say about God is true, and none of it is adequate, because we speak of him by analogy. + Aquinas explains this with the word healthy, and his example works as well at a kitchen table as it did in a lecture hall. You call a salad healthy, you call your neighbour healthy, and you call a blood test healthy. Now the word is plainly not being used in three unrelated senses, because all three uses have something to do with health. But it is not being used in one flat sense either, since the salad does not have health the way your neighbour does. Look at what each one is actually doing and the pattern comes clear: the salad causes health, the test signals it, and the neighbour is the one who has it. That gives us the three possibilities, and they are worth having by name. A word can be used univocally, which means in exactly the same sense of two things: "animal" said of a dog and of a horse. It can be used equivocally, which means in two unrelated senses that happen to share a sound: the bank of a river and the bank that holds your money. Or it can be used analogically, in senses that are genuinely different and genuinely related, which is what happens with healthy. Our words for God, Aquinas argues, work the third way, and the quickest way to see why is to watch what goes wrong on the other two. If "good" and "wise" mean exactly what they mean when said of us, then God turns out to be a very large version of a creature, which he is not. If instead they mean something wholly unrelated to what they mean in our mouths, then we know nothing whatever about God, and every argument from the world to God collapses into a pun. Paul would not then be able to say that God’s invisible attributes have been "clearly perceived, ever since the creation of the world, in the things that have been made" (Romans 1:20). The pastoral payoff here is larger than it looks. It means that when Scripture calls God a father, the word is telling the truth about him and is not a polite fiction we agree to use. It means, further, that fatherhood is more fully in God than in any human father, rather than the other way round; we are the copies, not the originals, and a good father is a faint likeness of God rather than God being a projection of a good father. And it means that a Christian can say a great deal about God, and say it confidently, while cheerfully admitting that he has not been comprehended.

(Q) "Univocal predication is impossible between God and creatures ... Therefore it must be said that these names are said of God and creatures in an analogous sense, i.e. according to proportion." + Source: Thomas Aquinas, Summa Theologiae I, question 13, article 5 (Fathers of the English Dominican Province translation, 1920). The question is whether what is said of God and of creatures is said in the same sense. Aquinas answers no to that, no to the opposite suggestion that the words are merely equivocal, and gives the doctrine of analogy as the way between them (T2). "Predication" here just means saying something of a subject, as calling a man wise says wisdom of him.

(T3) Grace does not destroy nature but perfects it. + A good piano teacher taking on a self-taught student does not begin by telling him to forget everything he knows. She works with the hands he already has, corrects what is wrong, and builds on what is right, and at the end he can play things he could not have reached on his own. That is roughly the shape of the sentence Aquinas is most quoted for. Two terms are doing the work in that sentence, and both are worth having straight. Nature is what a thing is and what it can do by its own powers: a bird can fly, a man can reason and choose. Grace is God’s own life given as a free gift, lifting a creature toward an end its nature could never have reached under its own steam. The question in the thirteenth century, and in every century since, is what the second of these does to the first. Does the gift cancel the creature, so that reason has to be silenced before faith can speak? Aquinas says no, and he says it in eight words that have carried an entire tradition behind them. The consequences run through everything he wrote. If grace perfects nature rather than destroying it, then philosophy is not an intruder in theology but a servant of it, and a pagan can turn out to be right about something. Aquinas quotes Aristotle so constantly that the Summa can simply call him "the Philosopher," and Averroes, a Muslim, "the Commentator," with no further introduction needed. He cites Maimonides, a Jewish rabbi, as an authority on how carefully we must speak about God, and Avicenna, a Muslim, on the difference between what a thing is and the fact that it is. He also argues hard against every one of them wherever he thinks they have gone wrong. That combination, of taking an opponent seriously enough to learn from him and seriously enough to refute him, is what the eight words look like when somebody actually lives by them.

(Q) "Since therefore grace does not destroy nature but perfects it, natural reason should minister to faith as the natural bent of the will ministers to charity." + Source: Thomas Aquinas, Summa Theologiae I, question 1, article 8, reply to objection 2 (Fathers of the English Dominican Province translation, 1920). The objection he is answering says that bringing human reasoning into theology cheapens it, since arguing from authority is the weakest kind of proof there is. His reply draws a distinction. Argument from human authority is indeed weak, he grants; argument from what God has revealed is the strongest there is; and reason comes into theology as a servant of faith rather than as a competitor to it (T3).

(T4) Reason can reach a long way toward God and not far enough, so the rest had to be revealed. + If reason can get as far as a first cause, why did anyone need a Bible? That is a fair question, and Aquinas thought so too: he opens the Summa with it, in the very first article of the whole work, and he gives two answers. Both turn on revelation, meaning what God has made known about himself rather than what we worked out for ourselves. The first answer is about the destination. A human being is made for an end that outruns anything reason could work out on its own: not merely to know that there is a God, but to be brought into God’s own life. Nobody reasons their way to the Trinity, or to a God who becomes a man and dies, and unless we are told about the end we are aimed at, we cannot aim at it. The second answer is the humane one, and it is easy to read straight past. Even the truths about God that reason can in principle reach, it reaches badly. Such knowledge, Aquinas says, would come to only a few people, after a long time, and mixed with many errors. Think of what it would take to work out your own medicine from first principles, with no doctor and no textbook. It is possible for somebody, in a way, and you would be dead long before you finished. Human salvation, he says, cannot be left to that. So the same truths a philosopher might slowly argue his way to are also handed over plainly, on God’s own authority, where a farmer can have them at once and get on with his life. This is the settlement that made his whole project possible, and it is worth stating slowly. Some truths about God reason can establish, some it cannot, and the two kinds never contradict each other, since one and the same God is the author of the world reason studies and of the revelation faith receives. So when an apparent conflict does arise, and they do arise, either the reasoning is faulty or the reading of Scripture is, and Aquinas is willing to say either one. On the age of the universe he thought Aristotle’s arguments for an eternal world were not conclusive, and he also thought the arguments of his fellow Christians against it were not conclusive; he held that the world began because Genesis says so, and he told his own side to stop pretending they had proved it.

(Q) "It was necessary for man’s salvation that there should be a knowledge revealed by God besides philosophical science built up by human reason ... the truth about God such as reason could discover, would only be known by a few, and that after a long time, and with the admixture of many errors." + Source: Thomas Aquinas, Summa Theologiae I, question 1, article 1 (Fathers of the English Dominican Province translation, 1920). The opening argument of the Summa: why a revealed teaching is needed alongside philosophy (T4). "Science" in this translation renders the Latin scientia, which means an organized body of knowledge rather than laboratory work.

(T5) Nothing less than seeing God will make a human being happy. + Every parent has watched this happen. The child wants the bicycle more than anything in the world, gets the bicycle, is happy for a fortnight, and then wants the next thing. Adults run the same pattern with better vocabulary: the promotion, the house, the qualification. Aquinas builds a whole moral theology on the observation, and on the refusal to treat it as a joke. He argues it out by asking what the mind is actually for. The intellect wants to know what things are, and when it knows an effect without knowing its cause it goes looking for the cause; that restlessness, he says, is exactly what wonder is. Now suppose someone reasons all the way to a first cause and knows for certain that God exists. There is still something he does not know, namely what God is, and so the wanting has not stopped, any more than the child’s wanting stopped at the bicycle. It follows that no amount of knowing about God is going to satisfy a human being. Only seeing God as he is would do it, and the tradition gave that its own name: the beatific vision, meaning the direct sight of God himself, which Scripture promises to the pure in heart (Matthew 5:8). Two things follow from that, and both are worth holding on to. The first is that the end in question is far beyond us. No creature can climb into the life of God under its own strength, which means the very thing we are made for can only ever arrive as a gift. "Beloved, we are God’s children now, and what we will be has not yet appeared; but we know that when he appears we shall be like him, because we shall see him as he is" (1 John 3:2). The second is that his ethics is not a rulebook bolted on afterwards, the way a list of house rules is nailed up in a rented kitchen. Courage, justice, temperance and the rest are simply the shape a life takes when it is genuinely aimed at the end it was made for. That is why Aquinas can spend hundreds of pages on ordinary virtues and ordinary vices, on anger and lying and money, and still be writing about God the whole time.

(Q) "Final and perfect happiness can consist in nothing else than the vision of the Divine Essence." + Source: Thomas Aquinas, Summa Theologiae I-II, question 3, article 8 (Fathers of the English Dominican Province translation, 1920). The conclusion of his long treatment of happiness, which had already worked through wealth, honour, fame, power, bodily goods, pleasure and even the contemplative life of the philosophers, and found each of them unable to still the wanting (T5). "Essence" here means what God is in himself, as opposed to what can be gathered about him from his effects. Paul says the same thing in his own way: "For now we see in a mirror dimly, but then face to face" (1 Corinthians 13:12).

(Q) "We purpose in this book to treat of whatever belongs to the Christian religion, in such a way as may tend to the instruction of beginners." + Source: Thomas Aquinas, Summa Theologiae, prologue (Fathers of the English Dominican Province translation, 1920). He goes on to say why he is writing at all: students, he thought, were being worn out by useless questions, by material presented in whatever order the occasion happened to suggest, and by endless repetition. The book meant for beginners went on to displace Lombard’s Sentences as the text theology students were set to comment on, and it has been argued over line by line ever since.

What the Church Made of Him

(†) His own university censured him within three years of his death, and Rome canonized him within fifty. + Aquinas was not a safe figure in his own lifetime, and he was less safe in the years immediately after it. In March 1277 Étienne Tempier, the bishop of Paris, condemned two hundred and nineteen propositions. The target was the radical Aristotelians, but a number of the articles struck at positions Thomas himself held, and eleven days later the archbishop of Canterbury, Robert Kilwardby, censured related theses at Oxford. For a generation after his death, teaching Thomas at Paris meant teaching under a cloud. His order backed him, and that made the difference. The Dominicans made his works required reading and defended him in print, and slowly the tide turned. He was canonized on 18 July 1323 by Pope John XXII, and two years later the bishop of Paris formally revoked the censures so far as they touched Thomas’s teaching. In 1567 Pius V named him a Doctor of the Church, a title the Catholic Church reserves for writers it regards as teachers of the whole church, which ranked him with Ambrose, Jerome, Augustine and Gregory. Then in 1879 Leo XIII’s Aeterni Patris, an encyclical, meaning a letter circulated to the bishops of the world, made his method the standard of Catholic philosophy and theology. That is why a hundred years of seminary manuals were built on him, and why a good deal of twentieth-century Catholic thought is either an application of Thomas or an argument with him.

(†) He made Aristotle safe to read, and what had been banned became the syllabus. + The dates tell this story better than any summary could. In 1210 a council at Paris forbade the teaching of Aristotle’s books on natural philosophy. In 1215 the university statutes repeated the ban. In 1231 Gregory IX ordered the books examined and purged of error before anyone could use them. And by the middle of the century the arts faculty was lecturing on the whole lot of them anyway, which left the theologians with a decision they could no longer put off. Thomas’s answer was neither to shut the books nor to swallow them. He wrote line-by-line commentaries on twelve of Aristotle’s works, not in order to praise them but in order to establish exactly what they said, and then he argued against Aristotle wherever he thought Aristotle was wrong: on whether the world had a beginning, on whether God knows and cares for each of his creatures, on whether the happiness a human being is made for can be had in this life at all. Anyone who has taken advice from a doctor who is excellent on some matters and out of date on others knows the operation from the inside. You do not throw the advice away, and you do not swallow it whole either. You sort it. The habit long outlived the particular books, and it is the habit rather than the books that matters now. What Christians learned from Thomas is that a body of secular knowledge can be examined on its own terms, on its own evidence, without being treated as either scripture or poison, and that is the posture a Christian can bring to a scientific claim today.

(†) The questions he framed have outlasted the school that carried his name, and are argued in every communion. + The Reformers had hard things to say about scholastic theology, which is the technical, objection-and-reply theology of the medieval schools, and Luther in particular attacked the use of Aristotle in the classroom. That is the part everyone remembers. What gets remembered less is that the Protestant scholastics of the following century, men like Girolamo Zanchi, Francis Turretin and John Owen, went on working with the same vocabulary about being, cause and essence that Thomas had refined, so that their doctrine of God stands a good deal closer to his than either side’s slogans would suggest. In the twentieth century Karl Barth rejected natural theology root and branch, that is, any attempt to reach God by reasoning up from the world instead of listening to God make himself known, and he made Aquinas the great example of the thing he was rejecting. That argument is still live. It is also a genuinely Christian argument, a disagreement between believers about how God is known, rather than a fight between Christians and outsiders. Meanwhile his arguments came back through a door nobody was watching. Analytic philosophers of religion in the second half of the twentieth century, trained in a tradition with no particular affection for the Middle Ages, found that his questions were the ones they were already asking and that his answers repaid study: Elizabeth Anscombe and Peter Geach, Anthony Kenny, Norman Kretzmann and Eleonore Stump. The contingency argument, which is the third of the five ways in modern dress, is defended today by philosophers who owe no loyalty at all to the thirteenth century. So are the questions that surround it: divine simplicity, the claim that God is not assembled out of parts or properties, God’s relation to time, and how a creature can be genuinely free while God is the first cause of everything there is. Those discussions still run largely along the lines he drew.

(†) Where his own record is open to criticism: he argued that obstinate heretics should be put to death, and took Aristotle’s account of women on trust. + The first of the two is much the harder, and there is no softening it, because it is his own considered teaching and not a remark made in passing. Asked whether heretics are to be tolerated, he answers that on the church’s side there must be patience, with a first and a second warning and real hope of a change of mind, but that a settled heretic may be excommunicated, meaning cut off from the church’s worship and sacraments, and then handed over to the secular power, meaning the civil ruler, for execution. His reasoning is an argument from the lesser case to the greater, of the kind he uses everywhere, and it is chilling precisely because it is so orderly: "For it is a much graver matter to corrupt the faith which quickens the soul, than to forge money, which supports temporal life." That this was the common assumption of thirteenth-century Christendom is a fact about the century. It is not a defence of the man who wrote it down more clearly than anyone else. Christians across every tradition now reject it, and they reject it on grounds available in the New Testament he had in front of him: the weapons of our warfare are not of the flesh (2 Corinthians 10:4), the servants are told to let the weeds grow with the wheat until the harvest (Matthew 13:29-30), and the apostles answer error by argument and by patient teaching. Aquinas of all people should have felt the force of that, since his own order was founded to persuade rather than to compel, and since the whole logic of his account of faith is that belief is an act of the will that cannot be coerced into being genuine. The second fault is smaller but it is real. Following Aristotle’s biology, which was the best available science of the day and happened to be wrong, he writes that as an individual the female is "defective and misbegotten," the result of something having gone slightly astray in generation. He immediately adds that women are no accident in the intention of nature, which is God’s intention, so that God made both male and female deliberately, and he is clear elsewhere that both bear God’s image (Genesis 1:27). But the borrowed embryology was simply false, and he did not stop to question it. There is a fair reminder in that about the man who taught the church how to sort a philosopher’s truths from his errors. He did not catch every one of them himself, and he would have been the first to want the correction made.